posting_date = models.DateTimeField(auto_now_add=True)

# purge_old_data.py

from django.core.management.base import BaseCommand,CommandError
from cus_leads.models import CustomerLeads 
from datetime import datetime,timedelta

class Command(BaseCommand):
    help = 'Delete objects older than 10 days'

    def handle(self,*args,**options):
        CustomerLeads.objects.filter(posting_date__gte=datetime.now()-timedelta(days=10)).delete()
        self.stdout.write('Deleted objects older than 10 days')

python 

cus_leads/
    __init__.py
    models.py
    management/
        __init__.py
        commands/
            __init__.py
            purge_old_data.py
    tests.py
    views.py